Ok, many thxSorry, I wasn't clear, the call you heard has a tone colour (not the best word I think) that travels a long way in forests, just like the sound of an Oriole.
A few times I've seen an Oriole singing in an open field and then the sound almost disappears. However, in a forest it's song can be heard a mile away. It has a pitch, tone, resonance that is completely 'adapted' to a forest. The sound of your bird has the same characteristics and that's why I think it's a bird from a rainforest.